Americans are about 20% more likely to experience memory problems if they lived in areas with high levels of atmospheric lead, according to a study of over 600,000 adults over the age of 65 released at the  Alzheimer’s Association International Conference in Toronto on Tuesday.

Researchers examined how exposure to airborne lead between 1960 and 1974, when leaded gasoline use was at its highest, may affect brain health later in life. 

They calculated exposure to historical atmospheric lead levels  (HALL) by area and linked it to self-reported memory problems from two American Community Surveys (conducted between 2012 and 2021) involving over 500,000 people. 

Some 17-22% of people living in areas with moderate, high or extremely high atmospheric lead reported memory issues.

“Our study may help us understand the pathways that contribute to some people developing dementia and Alzheimer’s disease,” said Dr Eric Brown, lead author and associate chief of geriatric psychiatry at the Centre for Addiction and Mental Health in Toronto.

Lead was originally added to gasoline to increase performance until researchers determined it posed serious risks to health and the environment. The more than 20-year-long phase-out of leaded gas began in 1975.

“When I was a child in 1976, our blood carried 15 times more lead than children’s blood today,” said Esme Fuller-Thomson, senior author of the study and a professor at the University of Toronto’s Faculty of Social Work.

“An astonishing 88% of us had levels higher than 10 micrograms per deciliter, which are now considered dangerously high.”

While the risk of atmospheric lead has decreased, other sources of exposure remain, such as old lead paint and pipes. Those who have been exposed to atmospheric lead should focus on reducing other risk factors for dementia, including high blood pressure, smoking and social isolation, said Brown.

“Research suggests half the US population – more than 170 million people – were exposed to high lead levels in early childhood. This research sheds more light on the toxicity of lead related to brain health in older adults today,” said Dr Maria Carrillo, Alzheimer’s Association chief science officer and medical affairs lead.

Another study reported at the conference found that older adults who live about three miles from a lead-releasing facility – such as glass, ready-mixed concrete or computer and electronics manufacturers – are more likely to have memory and thinking problems than those who live farther away. 

Lifestyle interventions help slow cognitive decline

Meanwhile, in better news, older adults at risk for cognitive decline and dementia who were actively encouraged to adopt healthy lifestyles were able to slow memory loss, the conference heard.

A study of over 2,000 people compared the impact of a structured lifestyle intervention with a self-guided intervention and found that, while both interventions helped, those in the more intense intervention had better success at slowing cognitive decline.

Both interventions focused on physical exercise, nutrition, cognitive challenge and social engagement, and heart health monitoring, but differed in intensity, structure, accountability and support provided.

In the structured lifestyle group, participants attended 38 facilitated peer team meetings over two years. They were provided with an activity programme with measurable goals, encouraged to eat according to the MIND diet, given cognitive challenges and other intellectual and social activities. Their progress was reviewed regularly.

In the self-guided lifestyle intervention, participants attended six peer team meetings to encourage self-selected lifestyle changes.

Participants in the structured intervention showed greater improvement on global cognition, protecting cognition from normal age-related decline for up to two years. 

The results of the study, called US POINTER, were reported for the first time at the AAIC conference and published in the Journal of the American Medical Association (JAMA).

“As the burden of dementia grows worldwide, US POINTER affirms a vital public health message: healthy behaviour has a powerful impact on brain health,” said Dr Joanne Pike, Alzheimer’s Association president and CEO.

“This is a critical public health opportunity. The intervention was effective across a broad, representative group – regardless of sex, ethnicity, APOE [gene] genetic risk, or heart health status – demonstrating its applicability and scalability for communities across the country,” added Pike. 

“The positive results of US POINTER encourage us to look at the potential for a combination of a lifestyle program and drug treatment as the next frontier in our fight against cognitive decline and possibly dementia.”

Image Credits: Dawn McDonal/ Unsplash, Photo by Steven HWG on Unsplash.